If pSegment and pSegmentState are both NULL, all music stops, and all currently cued segments are released. If either pSegment or pSegmentState is not NULL, only the requested segment states are removed from the performance. If both are non-NULL and DMUS_SEGF_DEFAULT is used, the default resolution from the pSegment is used.

If you set all parameters to NULL or 0, everything stops immediately, and controller reset messages and note-off messages are sent to all mapped performance channels.